EP1797357B1 - Transmission device for variable speed motor ancillary or accessory, motor equipped with same and applications - Google Patents

Description

The present invention relates to a device for transmitting at least two ratios for driving an apparatus from a variable speed motor, in particular for driving for example a supercharger, an air conditioning compressor, or an electric machine, from an engine, typically a heat engine, of a motor vehicle.

The present invention also relates to a supercharged heat engine equipped with a transmission device according to the invention.

The present invention furthermore relates to various applications of the transmission device according to the invention.

The devices of the type indicated above are typically driven by a belt from the vehicle engine shaft. The apparatus is therefore subject to variations in the rotational speed of the vehicle engine. However, this type of device often has a relatively narrow effective operating range, narrower than the range of rotational speeds of a vehicle engine. It is therefore impossible with a single transmission ratio between the drive motor and the device, to ensure a constantly optimal operation of the device.

Therefore, the transmission ratio is usually chosen to take into account, on the one hand, the maximum speed of rotation of the apparatus, which must not be exceeded, particularly when the engine is operating near its maximum rotational speed, and on the other hand so that the speed of operation of the device is optimal when the engine runs at its speed (rotational speed) the most common.

However, with such an adjustment, the device often has a very low efficiency when the engine is running at idle or very low speed. This is very disadvantageous in convenient. For example, the need for air conditioning in a vehicle is greater when the speed of travel is very low or zero. Other examples, for a heat engine to have a favorable characteristic curve of its engine torque as a function of the speed of rotation, it is generally desired that the torque be high for a relatively low rotational speed. With regard to an electric machine, it would be preferable to recharge the storage battery when the engine is idling, rather than taking the power from the engine when it is needed to propel the vehicle.

Multi-speed transmission devices have already been developed to overcome the above disadvantages. However, these transmission devices are controlled by the engine electronics or even the vehicle, according to indications given by sensors. In addition, electric or hydraulic actuators are required. In total, the known type of transmission device is complex and its interconnection with the vehicle's electronic network is a potential source of complex faults.

The DE-A-2 303 562 describes a device according to the preamble of claim 1, comprising a direct drive clutch whose driving member is driven by a screw-nut connection which is part of the stabilizing means. When the clutch is engaged, the axial force generated by the screw-nut connection acts on clutch pads, tending to keep the clutch in the engaged state. Centrifugal flyweights instead tend to disengage the clutch.

The GB 795,019 and the FR 2,668,231 describe transmission devices for driving the vehicle itself, and not for an accessory or auxiliary in the vehicle.

The EP 0 314 214 and the US 5,011,463 describe transmissions for ancillary apparatus that do not involve forces that vary according to the transmitted torque.

The object of the present invention is to overcome these disadvantages and in particular to present a transmission device that meets the needs essentially autonomously.

According to the invention, the at least two gear transmission device for driving an apparatus from a variable speed motor, such as a vehicle engine, comprising a gear mechanism, a selective coupling means capable of two states corresponding to a low transmission ratio and a high transmission ratio in which the apparatus is driven at a higher speed than in the low gear ratio for the same rotational speed of the engine, at least one force generating means for generating a variable actuating force, stabilizing means for generating a varying stabilizing force as a function of a rotational torque in the device, and at least one biasing means for applying the variable actuating force and the stabilizing force by means of selective coupling, is characterized in that the stabilizing means comprises a toothed member of the gear mechanism and in that said organ the toothed tooth is unloaded in one of the two states of the coupling means, and undergoes in the other state of the coupling means a relative movement of meshing under load with generation of a tooth pressure having a component constituting the stabilizing force.

According to a second aspect, the invention relates to various applications of the device according to the first aspect, for driving a supercharger compressor of the engine, for driving a motor vehicle air conditioning compressor from the propulsion motor. of the motor vehicle, or for the connection between an electric machine and the propulsion motor shaft of the motor vehicle.

In addition, the invention relates to a heat engine equipped with a supercharger, characterized in that the supercharger is driven by the engine shaft. motor via a transmission device according to the first aspect.

Other features and advantages of the invention will emerge from the description below, relating to non-limiting examples.

• la figure 1 est une vue schématique en perspective d'un moteur selon l'invention ;
• la figure 2 est une vue du dispositif de transmission entraînant le compresseur du moteur de la figure 1, en coupe axiale ;
• les figures 3 et 4 sont des vues analogues à la figure 1 mais montrant l'application du dispositif selon l'invention à l'entraînement d'une machine électrique et respectivement d'un compresseur de climatisation.

In the accompanying drawings;

• the figure 1 is a schematic perspective view of an engine according to the invention;
• the figure 2 is a view of the transmission device driving the engine compressor from the figure 1 , in axial section;
• the Figures 3 and 4 are similar views to the figure 1 but showing the application of the device according to the invention to the drive of an electric machine and respectively an air conditioning compressor.

In the example shown in figure 1 , the supercharged heat engine 1 comprises a heat engine 2 typically of the piston type having a motor shaft whose one end not shown is connected to a gearbox 3 and the other end 4 carries at least one drive pulley 6 of accessories and auxiliaries. In the very simplified representation of the figure 1 no accessories are shown, and only one auxiliary is represented, namely a supercharger 7 which compresses the air sent into the intake manifold 8 of the engine 2. In practice, the path of the air between the compressor 7 and the manifold 8 can be more complicated than represented and go particularly through an inter-cooler to rid compressed air of excess calories generated by compression.

The compressor 7 is driven by a belt 9 connecting the pulley 6 to a driven pulley 11. The pulley 11 drives the compressor 7 via a three-speed transmission device 12 according to the invention.

Pulley 11 ( Figure 2 ) is keyed on an input shaft 13 of the device, which is secured to a planet carrier 14 of a first differential mechanism 16 in the form of an epicyclic gear train. The planet carrier 14 has distributed around the general axis 17 of the transmission device, pins 18 on which satellites 19 can rotate freely. The satellites 19 meshes with a planetary wheel 21 of the mechanism 16, located radially inside the satellites, and a ring gear 22 located radially outside the satellites. The sun gear 21 is secured to a disc 23 which can be selectively secured to the housing 24 of the transmission device by a selective coupling means constituted by a friction clutch 26. The clutch 26 comprises a clamping member 27 which is immobilized in rotation with respect to the housing 24 and which is axially movable relative to the housing 24 under the thrust of a compression spring 28 which tends to tighten the clutch 26 and thus real estate the sun gear 21 relative to the housing 24.

The ring gear 22 is integral with a bell 29 which constitutes the output of a first module of the transmission device. This output is prevented from turning less quickly than the input of the module, constituted by the input shaft 13, by means of a freewheel 31 or unidirectional coupling, installed between the shaft 13 and the bell 29.

The planet carrier 14 rotates centrifugal weights 32 which each carry a cam 33. When under the effect of centrifugal force the flyweights 32 pivot radially outwardly, their cam 33 pivots clockwise to the figure 2 which tends to push to the left of the figure 2 , relative to the planet carrier 14, a slider 34 rotated by the planet carrier 14 and supported by an axial abutment 36 on the disc 23 integral with the sun gear 21.

The differential mechanism 16 is helicoidal teeth. As a result, the gear pressure has not only a circumferential component for transmitting torque, but also an axial component which is opposed in the sun gear 21 and in the ring gear 22, while the satellites 19 are subjected to forces which balance. In the realization according to the figure 2 , the inclination of the teeth is chosen in relation to the direction of the engine torque to be transmitted so that the sun gear 21 is biased axially in the direction of the arrow Fp which compresses the axial stop 36 and therefore tends to prevent the weights 32 of rise up. Therefore, the axial thrust in the ring gear 22 is directed to the left of the figure 2 it is absorbed by an axial abutment 37 through which the bell 29 bears against the planet carrier 14, which is integral with the shaft 13 retained axially in its bearings relative to the housing 24.

In addition, on the opposite side to the axial abutment 36, the disc 23 is supported axially against the clamping member 27 by means of another axial abutment 38.

The operation of the first module which has just been described is as follows.

At rest, the springs 28 clamp the clutch 26 so that the sun gear 21 is immobilized. When the rotational speed of the shaft 13 is low, the centrifugal force of the weights 32, which is proportional to the square of the rotational speed of the input shaft 13, is itself very small and therefore the weights 32 are prevented from lifting by the force of the springs 28 and the axial force of the teeth F _P , which act via the abutment 36 and The module thus starts with the sun gear 21 stopped, so that the rotation of the planet carrier 14 with the input shaft 13 causes an increased speed rotation of the ring gear 22 and consequently the output bell 29. If the speed of the input shaft 13 reaches a certain high threshold which is even higher than the torque to be transmitted, as measured by the axial force F _P , is high, the Weights 32 tend to lift by pushing the disc 23 to the left against the force F _P. The disk 23 in turn tends to push, by means of the abutment 38, the clamping member 27 in the direction of loosening of the clutch 26 against the prestressing springs 28. Consequently, clutch 26 begins to slide, the sun gear 21 is released, it starts to rotate in the same direction as the planet carrier 14 and the bell 29, while the speed of rotation of the bell 29 decreases. When this speed becomes equal to the speed of the input shaft 13, the freewheel 31 couples directly the input shaft 13 with the bell 29. The torque is no longer transmitted by the differential mechanism 16, the pressure Toothed and with it the axial force F _{P are} canceled so that the weights 32 are now free to positively release the clutch 26 and the gear change that has just occurred is stabilized. The module has automatically switched from an overdrive report to a direct drive report.

The return to the overdrive ratio occurs when the rotational speed falls below a low threshold, well below the high threshold that triggered the direct switchover. When the low threshold is reached, the prestressing springs 28 have a sufficient force to push the clamping member 27 in the direction of the clamping of the clutch 26 against the centrifugal origin force generated by the weights 32 .

The friction in the clutch 26 restores a certain transmission of torque through the teeth, then even the transmission of the entire torque when this friction is sufficient to slow down the sun gear 21 and therefore to make accelerate the bell 29 beyond the speed imposed by the freewheel 31. Consequently, the latter becomes inactive for the transmission of torque. The reappearance of a torque in the teeth 21 makes reappear axial force F _P which, by reducing or even suppressing the radial displacement of the weights 32 via the axial abutment 36, at the same time helps the spring 28 to restore the conditions operating the mechanism 16 in its overdrive report.

The bell 29 is rotatably connected to a tubular shaft 43 freely rotatably mounted around the input shaft 13, which extends through the entire device as an axial support. The tubular shaft 43 is the input shaft of a second differential mechanism 46, which is therefore mechanically mounted in series with the first mechanism 16. The second mechanism 46 is functionally identical to the first mechanism 16 and therefore it will not be not redescribed in detail. It is capable, like the mechanism 16 and under conditions that are in principle similar, of establishing either a direct ratio or an overdrive ratio between its input member 43 and an output bell 59. In general, the reference numerals used for this second mechanism 46 are increased by thirty compared to those used for the homologous elements of the first mechanism 16. For direct engagement, the bell 59 is coupled with the tubular input shaft 43 by a freewheel 61. For the overdrive operation, a selective coupling means 56, consisting of a friction clutch, prevents the sun gear 51 from rotating relative to the housing 24. The ratio of the number of teeth between the ring gear and the sun gear is closer to 1 in the mechanism 46 than in the mechanism 16. Thus, in the second mechanism 46 the jump between the two ratios is smaller.

The bell 59 constituting the output member of the second module 46, is connected to an output shaft 71 of the transmission device 12 via a selective coupling means 72, consisting of a multi-disk clutch bath oil, part of a safety device 73 protecting the output shaft 71 and therefore the compressor 7 against the overspeeds. The clutch 72 is normally tightened by compression springs 74 which put it under prestressing. The springs 74 act by means of a clamping plunger 76 which can be pushed in the direction of loosening of the clutch 72, against the springs 74, by centrifugal weights 77 subjected to the rotational speed of the output shaft 71 and acting on the clamping member 76 via an axial stop 78. The axial stop 78 is necessary because the clamping member 76 rotates with the bell 59, so at a different speed of the output shaft 71 when the clutch 72 is loosened.

The overall operation of the transmission device of the figure 2 is the next.

At low speed, the two differential mechanisms 16, 46 operate in overdrive. The speed of the input shaft 43 in the second mechanism, of which the weights 62 of this second mechanism are integral, is therefore greater than that of the shaft 13 driving the weights 32 of the first mechanism. Therefore, when the rotational speed of the shaft 13 increases, it is first the weights 62 of the second mechanism 46 which cause the passage of it in direct drive. If the speed of the input shaft 13 continues to increase, the first mechanism 16 in turn passes in direct contact.

A transmission device has thus been realized which tends to regulate the operating speed of the compressor 7 to make it less dependent on the speed of rotation of the motor shaft, so that the compressor 7 operates as often as possible at its speed. optimal and in particular with a markedly improved efficiency for low revolutions of the engine.

The selective coupling means 26, 56 are friction clutches with an oil bath allowing a smooth change of the transmission ratios, without jerks.

The weights 32, 62 produce from the centrifugal force an axial force which is substantially proportional to the square of the rotation speed undergone by the weights. Thus, it is certain that the increase in the original centrifugal force is not totally counterbalanced by an increase in the resistance torque of the driven apparatus as a function of its rotational speed.

In the example of the figure 3 , a device 81 according to the invention is used to drive an electric machine 82 associated with the motor 2. The device 81 is a two-speed device entirely housed inside a cup 83 which is integral with the element of input of the transmission device and whose periphery forms a pulley for the transmission belt 84 between this pulley and the shaft 4 of the engine 2. The electric machine 82 may be a generator for recharging a storage battery, or a generator with starter function and / or with auxiliary power engine function adding its power to that of the engine 2. When the machine 82 works as a motor, the tooth reaction such as F _P at the figure 2 is reversed but the centrifugal force is relatively low so that the assembly can be calculated so that the overdrive operation (which is therefore a down-gear operation when considering the machine 82 as a motor), is possible.

In the example shown in figure 4 , a transmission device 81 similar to that shown in FIG. figure 3 is used to drive an air conditioning compressor 86. Again, when the rotational speed of the shaft 4 of the motor becomes low, the device 81 goes into overdrive ratio and increases the cooling capacity of the compressor 86.

Of course, the invention is not limited to the examples described and shown.

The invention is not limited to overdrive and direct drive reporting.

Claims (21)

1. A transmission device with at least two ratios for driving an apparatus (7, 82, 86) by a variable-speed engine (2), such as a vehicle engine, comprising:

   - a gear train (16, 46);

   - a selective coupling means (26, 56) capable of two states corresponding to a low gear ratio and to a high gear ratio in which the apparatus is driven at a higher speed than in the low gear ratio for a same rotation speed of the engine,

   - at least one force generating means (32, 62) to generate a variable actuating force;

   - a state-stabilizing means (21, 51) to generate a state-stabilizing force (Fp) that varies depending on a rotation torque in the device, and

   - at least one urging means (34, 36, 23, 38) to apply the variable actuating force and the state-stabilizing force to the selective coupling means (26, 56),

   characterized in that the state-stabilizing means comprises a toothed means (21, 51) of the gear mechanism and in that this toothed means is unloaded in one of the two states of the coupling means and is subjected in the other state of the coupling means to a relative meshing movement under load with generation of a teeth pressure having a component (Fp) constituting the state-stabilizing force.
2. A device according to claim 1, characterized in that the gear mechanism is a differential mechanism (16, 46) which operates in direct drive in one of the two states of the selective coupling means (26, 56), and in that the set of teeth (21, 51) is inactive for torque transmission during direct drive operation.
3. A device according to claim 1 or 2, characterized in that the selective coupling means (26) is in the disengaged state during direct drive operation.
4. A device according to one of the claims 1 to 3, characterized in that the state-stabilizing force (Fp) tends to put the selective coupling means in the engaged state.
5. A device according to one of claims 1 to 4, characterized in that the component (Fp) constituting the state-stabilizing force is the axial component of the pressure of a helical set of teeth of the toothed means (21, 51).
6. A device according to one of the claims 1 to 5, characterized in that the force generating means comprises a centrifuge means (32, 62) and the at least one urging means applies the centrifugally produced force in the direction tending to put the selective coupling means (26, 56) in its state corresponding to a low transmission ratio.
7. A device according to claim 6, characterized in that the centrifuge means (32, 62) is subjected to a rotation speed at the input of the gear train (16, 46).
8. A device according to one of claims 1 to 7, characterized in that the low gear ratio is a direct drive ratio and the high gear ratio is an overdrive ratio.
9. A device according to claim 9, characterized in that the selective coupling means (26, 56) is a clutch for selective immobilization of a reaction element (21, 51) of the gear train of differential type.
10. A device according to one of the claims 1 to 9, characterized in that said device comprises a one-way clutch (31, 61) preventing an output element (29, 59) from turning slower than an input element (13, 43) when the selective coupling means (26, 56) is in the disengaged state.
11. A device according to one of claims 1 to 9, characterized in that the selective coupling means (26, 56) is in the clutched state for operation in the high ratio, and, from the clutched state, when the torque to be transmitted exceeds a threshold, can allow a sliding until re-establishing the low ratio defined by a one-way clutch.
12. A device according to one of claims 1 to 11, characterized in that a clamping element (27) of the selective coupling means is acted upon by a resultant of forces originating from:

    - at least one spring (26) tending to put the selective coupling means (28, 58) in the engaged state;

    - an element (34) subjected to a centrifugally produced force, constituting the variable actuating force and tending to put the selective coupling means (28, 58) in the disengaged state;

    - an element (23) subjected to the state-stabilizing force (Fp) promoting the engaged state.
13. A device according to claim 12, characterized in that the element (34) subjected to a centrifugally produced force bears onto the clamping element (27) by way of the element (23) subjected to the state-stabilizing force, in particular the axial component of the set of teeth thrust (Fp).
14. A device according to claim 12 or 13, characterized in that the selective coupling means (26, 56) selectively couples a case (24) of the device with the element (33) subjected to the state-stabilizing force.
15. A device according to one of claims 1 to 14, characterized by comprising two sub-assemblies (16, 46) each with two ratios, mounted in series.
16. A device according to one of claims 1 to 15, characterized by comprising at the output a safety clutch with centrifugal control (73) for declutching the output (71) of the device in case of an overspeed at the output.
17. A device according to one of claims 1 to 16, characterized by comprising an input element in the form of a pulley (83) forming a cup at least partially enclosing the device.
18. A use of the device according to one of claims 1 to 17 for driving an engine supercharging compressor (7).
19. A heat engine equipped with a supercharging compressor (7), characterized in that the supercharging compressor (7) is driven by the shaft (4) of the engine (2) via a transmission device (12) according to one of claims 1 to 17.
20. A use of the device according to one of claims 1 to 17 for driving a motor vehicle air-conditioning compressor (86) from the propulsion engine (2) of the motor vehicle.
21. A use of the device (81) according to one of claims 1 to 17 for connecting an electric machine (82) to the propulsion engine (2) of the motor vehicle.

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